hi I'm thinking that u should add a custom egg! I would say like the egg is called a mega egg! this egg contains a mega scizor, mega kangaskan, mega charizard, mega blastoise, mega venasaur, mega ttar, mega ampharos, mega mew two but the mega mew two is like a 25% chance of getting it also u should add a early gen 3 Pokémon like a metagross.
I would say it's a bit too early for mega Pokemon. Since we're only in gen 2 and mega stones/Pokemon got released in gen 4
This is a silly egg considering pokemon dont come mega evolved ... they mega evolve in game . And megas only game in gen 6
This idea isn't bad, actually i'd like to see this in the game after gen 4/5. Right now mega pokemon wouldn't fit.